• Journal of electromagnetic engineering and science
• /
• v.15 no.2
• /
• pp.111-114
• /
• 2015

In this paper, we have proposed dual-band Phi-shaped slot gap filler antenna for satellite internet service applications. Some properties of the antenna such as return loss, radiation pattern, and gain have been simulated and measured. The proposed antenna has a Phi-shaped slot on the circular patch and is fabricated on the TLX-9 substrate. The radius of the circular patch is 25 mm, and it has a coaxial feeding structure. The dual-band Phi-shaped slot gap filler antenna has high-gain, small-size, simple-structure, and good radiation patterns at each band. The operating frequency band can be tuned by adjusting the length AL and FL of the Phi-shaped slot.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.29 no.1
• /
• pp.1-9
• /
• 2018

In this paper, we propose a film-type dual-band frequency selective structure for improving the wireless communication environment in a building. The proposed frequency-selective structure is a miniaturized structure that can control the resonant frequencies of 2.4 GHz and 5 GHz dual band through simple design parameters. We fabricated the frequency-selective surface by screen printing using conductive ink on a thin transparent film and confirmed its performance by measurement. We analyzed the attenuation performance of the unnecessary signal from the outside when the frequency-selective structure designed using the software to analyze the propagation environment performance is applied to the building. To verify the analytical results, the signal strength of the indoor environment was measured by applying the frequency-selective film fabricated on the inner wall of the actual building. The measurement results show that the dual-band frequency-selective film has 29.4 dB and 15.94 dB attenuation performance in the 2.4 GHz and 5 GHz, respectively.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.11a
• /
• pp.387-388
• /
• 2008

This paper presents the design approach and test results of the Q-band precision subminiature coaxial adaptor based on transmission line theory using multi-step impedance and air-holes to increase its cutoff frequency. In order to increase the frequency performance, the adaptor is designed with hooked structure, fixing step, multi-air-holes, and outer conductor. The return loss increments due to the hooked structure and multi air-holes are minimized to 2 dB and 1.5 dB, respectively. A VSWR(Voltage Standing Wave Ratio) of <1.2 is obtained from DC to 40 GHz, while guaranteeing the durability of the adaptor from room-temperature$(25^{\circ}C)$ to $120^{\circ}C$.

• Bulletin of the Korean Chemical Society
• /
• v.28 no.12
• /
• pp.2333-2337
• /
• 2007

Nanoporous TiO2 and ZrO2 thin films were spin-coated using a surfactant-templated approach from Pluronic P123 (EO20PO70EO20) as the templating agent, titanium alkoxide (Ti(OC4H9)4) as the inorganic precursor, and butanol as a the solvent. The control of the electronic structure of TiO2 is crucial for its various applications. We found that the band gap of the hybrid nanoporous thin films can be easily tuned by adding an acetylacetonestabilized Zr(OC4H9)4 precursor to the precursor solution of Ti(OC4H9)4. Pores with a diameter of 5 nm-10 nm were randomly dispersed and partially connected to each other inside the films. TiO2 and ZrO2 thin films have an anatase structure and tetragonal structure, respectively, while the TiO2-ZrO2 hybrid film exhibited no crystallinity. The refractive index was significantly changed by varying the atomic ratio of titanium to zirconium. The band gap for the nanoporous TiO2 was estimated to 3.43 eV and that for the TiO2-ZrO2 hybrid film was 3.61 eV.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.22 no.5
• /
• pp.787-793
• /
• 2018

In this paper, we propose a new single carrier - frequency domain equalization (SC-FDE) structure to cope with narrow band interference. In the conventional SC-FDE structure, when a high-power narrow band interference exists, channel estimation and data recovery is difficult. To relieve from this problem, this paper proposes a new SC-FDE frame structure to enable frequency-domain channel estimation in the environments that exist narrow band interference. Specifically, in the conventional method, the channel estimation is performed in time-domain first and from that, the frequency-domain channel is obtained by Fourier transform. In contrast, we proposed a new SC-FDE structure to enable frequency-domain channel estimation directly from received signals without time-domain channel estimation. The receiver performance improvement is verified through computer simulation. According to the results, the proposed technique can detect the signal with less than 2 dB loss compared with jammer-free environments, while the conventional method does not communicate with each other.

• Journal of electromagnetic engineering and science
• /
• v.5 no.4
• /
• pp.208-212
• /
• 2005

In this paper, we introduced a band-pass filter employed the PBG structure and the aperture on the ground together. The harmonics of band pass filter have been suppressed by employing the PBG structure and the bandwidth of it has been broadened by using the aperture on the ground. The designed PBG cells have three different sizes. The largest cells, the middle cells, and the smallest cells have suppressed the multiple of second harmonics, the multiple of third harmonics, and the multiple of fifth harmonics, respectively. The center frequency has been 2.18 GHz. The bandwidth has been increased from 230 MHz up to 310 MHz(80 MHz, about $35\%$) by the aperture and the ripple characteristics in passband have been improved and the harmonic frequencies have been suppressed about 30 dB by the PBG.

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2007.04a
• /
• pp.440-443
• /
• 2007

In this paper, microstrip antenna is designed for industrial-scientific-medical(ISM)band of S-Band. We proposed that radiation element of antenna, which is rectangle patch shape. The feeding structure used L-shaped structure. Center frequency and -l0dB bandwidth are investigated by change of length and width in patch plane. And maximum gain, front to back ratio and 3dB beam width is presented by simulation radiation pattern of antenna in frequency ISM Band. The center frequency is 2.45GHz, band width is $2.314{\sim}2.577GHz$ with 263MHz(11%). And the antenna maximum gain is 9.3dBi, 3dB beam width E-plane is $52.5^{\circ}$, H-plane is $64.7^{\circ}$.

• The Journal of the Acoustical Society of Korea
• /
• v.31 no.7
• /
• pp.472-479
• /
• 2012

This paper is aimed to design 9.2 kbps low bits late transform excitation coder that target to voice and audio signal. To set up low bit rate, we used Band-selection in frequency domain and gain-shape quantization and AbS structure. To decrease lots of calculation from ABS structure, we used each band IDFT and synthesis. And we designed non-transfer band for performance by inserting comfort noise. We propose coder that has low bit rate and similar performance comparing with original 10.4 kbps AMR-WB+ TCX mode.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.08a
• /
• pp.191-191
• /
• 2011

최근 투명전극 연구는 태양전지 및 디스플레이, LED 등 많은 분야에서 응용되며 또한 기술 개발이 활발하다. 그 중 전기 전도도가 우수하면서 밴드갭이 2.5 eV 이상으로 가시광 영역에서 투명하기 때문에 디스플레이의 투명전극으로 ITO (Indium Tin Oxide)가 많이 사용되고 있다. 본 실험에서는 RF magnetron sputtering법을 이용한 ITO의 증착시 산소 유량을 달리하여 제작한 박막의 Energy Band Structure를 ${\gamma}$-FIB system을 이용하여 측정하였다. ITO에 이온화 에너지가 24.5 eV인 He Ion source를 주사하였을 때 Auger self-convolution을 통해 이차전자의 운동 에너지 분포를 구하고, 이를 통해 ITO 내의 Energy Band Structure를 실험적으로 측정하였다.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.60 no.12
• /
• pp.2305-2310
• /
• 2011

This paper describes a design of dual band balanced amplifier using a lefted handed meta-material transmission line structure for high frequency application. Meta-material transmission lines have been known to have dual band frequency responses. A dual band branch line hybrid coupler is designed using the meta-material transmission lines, and measured at first. Two identical dual band amplifiers are also designed, built and tested using the same meta-material transmission structure. The proposed dual band balanced amplifier is composed of those dual band branch line hybrid coupler and amplifiers. In order to suggest an design example, a prototype of dual band balanced amplifier is built and measured at the dual frequencies, 1800MHz($f_1$) and 2300MHz($f_2$). The simulation and measurement show that the fabricated balanced amplifier operates well at the desired dual frequencies bands with the gain of 11.12dB and 17.67dB at $f_1$ and $f_2$, respectively, with a good agreement with the simulation results.